Computers communicate by transferring data, instructions, and information between devices using communications devices, channels, and protocols. A sender initiates the transfer, data is transmitted through a channel like cable or wireless media, and a receiver accepts the transmission. Common devices include modems, routers, hubs, and switches that connect components and route traffic. Networks connect multiple devices and come in different topologies like bus, ring, and star configurations. Networks can be intranets within an organization, extranets between groups, or the large global Internet system.

1. ISINFORMATION SYSTEMS
BY: JAN WONG
HELLO AND
WELCOME TO
Chapter Six:
COMMUNICATIONS &
NETWORKS
“How do systems communicate with one
another?”

2. Computers require a
combination of different
hardwares to communicate
with each other.
Did you know?
It is a process where two or more computers / devices
transfers data, instructions and information.

3. Here’s how computer / device
communications work.
Sender Receiver
Communications
Device
Communications
Device
Communications
Channel
Devices / Servers
Initiates the
transfer of data,
instructions or
information.
Devices / Servers
Accepts the
transfer of data,
instructions or
information.
Modem / Router /
Hub / Switch
Connects the
sending device to
the channel.
Modem / Router /
Hub / Switch
Connects the
channel to the
receiving device.
Coaxial Cable /
Fibre / Wireless
Media on which
data, instructions
or information
travel on.
Converts
digital signals
to analogue.
Converts
analogue signals
back to digital.
Transmits signals
to the correct
end point.
Data is transmitted
via digital signals
containing a
destination address.

4. Here’s how computer / device
communications work.
Sender Receiver
Communications
Device
Communications
Device
Communications
Channel
Devices / Servers
Initiates the
transfer of data,
instructions or
information.
Devices / Servers
Accepts the
transfer of data,
instructions or
information.
Modem / Router /
Hub / Switch / AP
Connects the
sending device to
the channel.
Modem / Router /
Hub / Switch / AP
Connects the
channel to the
receiving device.
Coaxial Cable /
Fibre / Wireless
Media on which
data, instructions
or information
travel on.
Internet, Web Browsing, Email, Social Media, Instant Messaging,
VoIP, FTP, Cloud Storage, Video Conference, Fax, Groupware &
Collaborative Tools, etc.
Example uses of communications technology:
Converts
digital signals
to analogue.
Converts
analogue signals
back to digital.
Transmits signals
to the correct
end point.
Data is transmitted
via digital signals
containing a
destination address.

5. Sender Receiver
Communications
Device
Communications
Device
Communications
Channel
Devices / Servers
Initiates the
transfer of data,
instructions or
information.
Devices / Servers
Accepts the
transfer of data,
instructions or
information.
Modem / Router /
Hub / Switch / AP
Connects the
sending device to
the channel.
Modem / Router /
Hub / Switch / AP
Connects the
channel to the
receiving device.
Coaxial Cable /
Fibre / Wireless
Media on which
data, instructions
or information
travel on.
• Modem: Connects to your Internet Service Provider (ISP)
using phone line or Fibre.
• Router: Joins networks together and routes traffic between
them (e.g. between your home internal network with the
internet). It usually has a built-in Switch.
• Access Point (AP): Usually wireless in nature that functions
the same as a Router.
• Hub / Switch: Forwards data from sender to receiver,
however Switches does it more efficiently as there is no
traffic collusion compared to a Hub.

6. Sender Receiver
Communications
Device
Communications
Device
Communications
Channel
Devices / Servers
Initiates the
transfer of data,
instructions or
information.
Devices / Servers
Accepts the
transfer of data,
instructions or
information.
Modem / Router /
Hub / Switch / AP
Connects the
sending device to
the channel.
Modem / Router /
Hub / Switch / AP
Connects the
channel to the
receiving device.
Coaxial Cable /
Fibre / Wireless
Media on which
data, instructions
or information
travel on.
• Physical Transmission Media: Wire, cable, and other tangible
materials used to send communication signals.
• Wireless Transmission Media Optic Media: Perfect when it is
inconvenient, impractical or impossible to install cables.
Each media type has a
different bandwidth limit.
Bandwidth: Amount of data that
can travel on the channel.

7. Let’s look at
Physical Transmission Media
Wire, cable, and other tangible materials used to send communication signals.
Used for telephone systems
and network cabling.
Used for cable television cabling.
Carries significantly more speed as data travels by
light. Less susceptible to interference (noise) and
more secure. Thinner and lighter.

8. Let’s look at
Wireless Transmission Media
Perfect when it is inconvenient, impractical or impossible to install cables.
Requires a direct light path,
common in remotes.
Distributes radio signals over both
short & long distances.
Form of broadcast radio for
mobile communications.
Distributes radio signals over both
short & long distances via a
microwave station.
Earth-based reflective dishes that
must be in straight line with no
obstructions.
Space station that receives microwave signals from
earth based stations to be amplified and broadcasted
back to any other earth-based stations.

9. A collection of devices
connected via
communication devices is
called a network.
Did you know?
Different network types and topologies has different
features.

10. ISSo, what is a network?
How does it look like?

11. This is how a network looks like.
Basic Network
(P2P)
Client / Server
Network

12. Common Types of
Network Topology
Bus / Linear Ring Star
All computers and
devices connect to
central cable.
Cable forms closed ring, or
loop, with all computers and
devices arranged along ring.
Data travels from device to
device around entire ring, in
one direction
All devices connect to a
central device, called hub.
All data transferred from
one computer to another
passes through hub.

13. Types of networks.
Intranet
(LAN / WLAN)
Extranet
(MAN / WAN)
Internet
Network in limited
geographical area such as
home or office building.
Network that connects
between networks, possibly
across cities and towns.
A global network that
covers large geographic
area.
Used in closed communities,
companies, or internal
networks for employees.
Allows customers or
suppliers to access a part of
company’s intranet.
May be a server or client that
exchanges information
across the globe.